| 
      2017  | 
      2018  | 
    ||||||||
Major goods/  | 
      Group  | 
      SMS  | 
      SMRT  | 
      SMT  | 
      Oth Op  | 
      Group  | 
      SMS  | 
      SMRT  | 
      SMT  | 
      Oth Op  | 
    
Sale of goods  | 
      89,716  | 
      35,958  | 
      35,707  | 
      13,231  | 
      4,819  | 
      96,154  | 
      39,918  | 
      39,350  | 
      15,043  | 
      1,843  | 
    
Rendering of services  | 
      3,108  | 
      146  | 
      2,800  | 
      49  | 
      112  | 
      3,644  | 
      414  | 
      3,162  | 
      67  | 
      —  | 
    
Rental income  | 
      1,065  | 
      —  | 
      1,065  | 
      —  | 
      —  | 
      1,112  | 
      —  | 
      1,112  | 
      —  | 
      —  | 
    
Total  | 
      93,906  | 
      36,114  | 
      39,574  | 
      13,281  | 
      4,937  | 
      100,924  | 
      40,343  | 
      43,624  | 
      15,111  | 
      1,846  |